In a typical binding line, a gathering chain for conveying a plurality of signatures along a gathering section of the binding line extends in a path along which a row of feeding devices, such as pockets (which are also called packer boxes), card-feeders, and SMUF and Dragon PTF devices, are disposed. The gathering chain forms a closed loop and includes a plurality of gathering pins disposed at spaced locations dividing the gathering chain into a plurality of chain spaces. The feeding devices are selectively operative to place printed signatures on selected chain spaces as the gathering chain advances along the length of the gathering section.
A typical chain space, for example, is initially empty, and the feeding devices selectively deposit signatures on the chain space atop previously-gathered signatures, if any. Thus, at the end of the gathering section, the chain space has a stack of signatures deposited thereon.
Each stack is transferred from the gathering section to a stitcher unless the stack is first rejected by a reject gate. The reject gate rejects a stack if a bit in a shift register corresponding to the chain space in which the stack was assembled is set, indicating that the stack was found to be defective by sensors located in the feeding devices or otherwise disposed adjacent the gathering chain.
If the shift-register bit corresponding to a particular chain space is not set (i.e., the stack of signatures in that chain space has not been found to be defective), the stack passes through the reject gate into the stitcher where the stack of signatures is stitched or stapled together to form a complete product or book. If necessary, the stitched books may then be trimmed to a uniform page size. Finally, the books are mailed or otherwise distributed.
In order for the binding line to operate properly and produce acceptable books, it is important to ensure that the machine cycle of each feeding device be synchronized with the position of the chain space on which the feeding device is to place a signature. Under a variety of circumstances, however, the synchronized operation of the feeding devices with respect to the gathering chain can be disrupted.
For example, because the gathering chain is typically up to one hundred feet long, it has a tendency to stretch under prolonged use.
In addition, there is occasionally a need to calibrate the binding line. For example, the chain-space-size is often changed to produce books of different sizes.
Still further, one or more of the feeding device is often replaced with a different kind of device for feeding a different kind of signature. For example, a card-feeder is a device for placing a card (such as a subscription-renewal card or an information-request card) on stacks of signatures.
Any of the above changes to the binding line can disrupt the synchronized timing of the feeding devices causing signatures to be misaligned in the stacks or even omitted altogether.
Moreover, if the feeding devices are not properly synchronized with the gathering chain, the shift-register contents, which ordinarily indicate which stacks are defective and which are acceptable, may be rendered invalid. In other words, for example, if a sensor of one of the feeding devices detects that a signature that should be present in a particular chain space is missing, the bit in the shift register corresponding to the particular chain space should be set, so that the stack in the particular chain space will thereafter be rejected by the reject gate. If the timing of the feeding devices is not properly synchronized, however, the detection of a missing signature may result in the wrong bit in the shift register being set. Consequently, a defective stack may be accepted, or a nondefective stack may be rejected, or both.
Previously, when an operator of a binding line identified a problem with the timing points of the feeding devices, it was necessary for an electrical technician to reprogram the timing points and shift-register positions of the feeding devices or the contents of the shift register using a portable programmable computer temporarily interfaced into the binding line controller. The binding line controller provided no means for an operator to independently make adjustments to machine timing. As a result, timing problems often have resulted in prolonged down time of the binding line causing undesirable lags in productivity. Moreover, the length of these lags is particularly problematic when a significant number of adjustments must be made to the binding line due to the sizeable number of feeding devices which are included in the binding line, and where each feeding device includes a number of sensors each of which has (1) an associated timing point and (2) an associated shift-register position, either or both of which may need to be adjusted. Still further, because a binding line is often reconfigured, such as to produce differently sized books, the above-described operator set-up procedure must often be repeated for each new binding line configuration.